1. Field of the Invention
This invention relates to a vehicle door latch and more particularly to a vehicle door latch designed to prevent the occurrence of a loud noise during operation.
2. Prior Art
According to the prior vehicle door latch disclosed in U.S. Pat. No. 4,073,519, as shown in FIG. 18, a latching member 52 first approaches a striker 54 when a vehicle door is closed. Subsequently, a wall surface 56 at the entrance of a recess 55 of the latching member abuts with the striker. After abutment, the latching member 52 is turned by the striker in the direction of an arrow 63 from the open position shown in FIG. 18 to the fully locked position shown in FIG. 19. During this turn, the striker 54 progressively goes into the recess 55 formed in the latching member 52 from the entrance to a deep part 59 of the recess 55. The above turning of the latching member 52 into the fully locked position also causes a fully locking tooth 62 to engage with a pawl 53. As a result, the fully locked state as shown in FIG. 19 is achieved.
During such operation of the latch, at the entrance part of the recess 55, a noise suppressor member 57 provided over the wall surface of the recess 55 on the preceding side in the turning direction of the latching member functions to prevent the occurrence of noise upon impact of the latching member 52 with the striker 54. However, when the impact quickly turns the latching member 52 in the direction of an arrow 63, a wall surface 58 at the entrance part of the recess 55 on the succeeding side in the turning direction of the latching member will hit against the striker 54, thereby producing a noise upon impact.
On the other hand, a width 60 of the recess 55 at the deep part 59 is generally designed larger than a design diameter of the striker 54. This results from the reason that, if the width 60 is designed equal to a typical diameter of the striker 54, in case of the striker 54 having an unexpectedly larger diameter due to the size tolerance, the striker 54 would be caught by the wall surface of the deep part 59 and become difficult to slip out therefrom when releasing the striker 54 which has been forced into the deep part 59. Of course, if the width 60 is set smaller than the diameter of the striker 54, the same phenomenon would occur. With the width 60 being larger than the diameter of the striker 54 as mentioned above, when the striker 54 goes into the deep part 59 of the recess during the closing process of the door, a play exists between the wall surface of the deep part 59 and the striker 54. Therefore, the latching member 52 becomes swingable relative to the striker 54. Upon swinging of the latching member 52, a wall surface 61 of the deep part 59 on the succeeding side will hit against the striker 54, thereby producing noise.
The aforementioned impact noise caused by quick turn of the latching member can be prevented by attaching a noise suppressor member over the wall surface 58 at the entrance of the recess 55 on the succeeding side. However, the wall surface 61 of the deep part 59 on the succeeding side serves as a surface with which is engaged the striker 54 in the fully locked position. For this reason, a noise suppressing member cannot be attached thereto. Thus, the presence of the above play inevitably causes objectionable noise.